//But can we glean anything about the country's overall attitude to Brexit 3 years on?//
Yes. The Remainers still want to remain. The Leavers still want to leave. The Leavers (whose view prevailed when they were asked what they wanted) have suffered three years of prevarication, procrastination, and downright incompetence and are no closer to seeing realised what their MPs promised than they were three years ago. The Remainers have concocted a number of reasons why we cannot leave with, in England & Wales at least, only the Liberal Democrats being honest enough to say that if they have their way, Brexit will not happen at all. The Leavers have watched whilst their Prime Minister has acquiesced to every demand made by the EU until she realised - what they knew from the outset - that the EU would never agree to granting us permission to leave without harsh conditions. The country thus faces leaving with a deal that has been soundly rejected or not leaving at all (Parliament having ruled that "No Deal" is akin to committing suicide).
It it any wonder that both camps have deserted the two main parties who have, in their own different ways, conspired to bring about this ludicrous state of affairs?